(1. 昆明理工大學(xué) 國土資源工程學(xué)院/有色金屬礦產(chǎn)地質(zhì)調(diào)查中心，西南地質(zhì)調(diào)查所，昆明 650093；
2. 中國科學(xué)院 地球化學(xué)研究所， 礦床地球化學(xué)國家重點(diǎn)實(shí)驗(yàn)室，貴陽 550081；
3. 中國有色金屬工業(yè)昆明勘察設(shè)計(jì)研究院有限公司，昆明 650051；
4. 云南迪慶礦業(yè)開發(fā)有限責(zé)任公司，香格里拉 674400)
摘 要: 羊拉銅礦床位于金沙江構(gòu)造帶中部，為滇西北地區(qū)最為典型的銅礦床，鉛鋅礦體為近年來的找礦新發(fā)現(xiàn)，鉛鋅成礦作用及其與銅礦體的成因聯(lián)系成為亟待解決的科學(xué)問題。本文在野外坑道編錄及室內(nèi)巖礦鑒定的基礎(chǔ)上，重點(diǎn)研究了鉛鋅礦體的稀土元素及C-O、S、Pb、Zn同位素地球化學(xué)。研究表明：①羊拉礦床的鉛鋅礦體主要為矽卡巖型，呈層狀、似層狀、脈狀、透鏡體狀分布于矽卡巖型銅礦體的邊緣，與矽卡巖型銅礦體共同產(chǎn)出，明顯具分支復(fù)合、尖滅再現(xiàn)的特征；其次為熱液脈型，呈不規(guī)則細(xì)脈狀充填于構(gòu)造破碎帶內(nèi)；與鉛鋅成礦作用相關(guān)的方解石可分為早階段方解石(Ⅰ)和晚階段方解石(Ⅱ)。②早成礦階段方解石(Ⅰ)主要呈他形晶不規(guī)則團(tuán)塊狀產(chǎn)出，ΣREE在24.05×10-6~104.50×10-6之間，δEu顯示正異常、δCe顯示弱負(fù)異常，稀土元素配分模式為輕稀土富集的右傾型曲線；δ13CPDB在-6.52‰~-4.07‰之間，δ18OSMOW在5.04‰~9.94‰之間，成礦物質(zhì)主要來源于花崗巖質(zhì)巖漿。晚成礦階段方解石(Ⅱ)呈脈狀產(chǎn)出，ΣREE在28.71×10-6~114.60×10-6之間，δEu顯示正異常、δCe顯示弱負(fù)異常，稀土元素配分模式為輕稀土富集的右傾型曲線；δ13CPDB在-3.81‰~-3.53‰之間，δ18OSMOW在14.36‰~17.30‰之間，成礦物質(zhì)來自于花崗巖質(zhì)巖漿與海相碳酸鹽巖的混合。③早、晚成礦階段方解石均為熱液成因，其稀土元素并無明顯差異。④38件硫化物的δ34S在-2.48‰~2.32‰之間，總硫同位素接近于零值，表明成礦物質(zhì)來源于地幔和深部地殼，屬巖漿源硫。⑤15件硫化物的鉛同位素變化范圍小，208Pb/204Pb= 38.7501~38.7969，207Pb/204Pb=15.7159~15.7248，206Pb/204Pb=18.3640~18.3874，表明鉛鋅礦體中鉛主要來源于上地殼。⑥5件閃鋅礦Zn同位素的δ66ZnJMC值在0.31‰~0.44‰之間，明顯大于其他矽卡巖型鉛鋅礦床，亦揭示成礦物質(zhì)Zn主要來源于巖漿。⑦羊拉礦床矽卡巖型鉛鋅礦體與矽卡巖型銅礦體在賦礦層位、形態(tài)產(chǎn)狀、礦物組合、礦石組構(gòu)、圍巖蝕變、控礦因素以及C-O、S、Pb同位素組成等方面均無明顯差異，反映鉛鋅礦體與銅礦體均為矽卡巖成因，鉛鋅礦體的形成稍晚于銅礦體，分布于銅礦體的邊緣。綜合上述資料，本文建立了羊拉礦床銅鉛鋅成礦模式。
關(guān)鍵字: 鉛鋅礦體；方解石；稀土元素；同位素；羊拉銅多金屬礦床；滇西北
（1. Faculty of Land Resource Engineering, Kunmming University of Science and Technology/Southwest Institute of Geological Survey Centre for Nonferrous Metals Resources, Kunming 650093, China;
2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
3. Kunming Prospecting Design Inst China Nonferrous, Kunming 650051, China;
4. Yunnan Diqing mining Co., Ltd. Shangrila 674400）
Abstract:The Yangla copper deposit which is located in the middle of Jinshajiang tectonic belt, is the most typical copper deposit in the northwest of Yunnan province. In recent years, Pb-Zn orebodies were newly discovered in the depth of Yangla copper deposit, Pb-Zn orebodies mineralization and its genetic relationship with copper ore bodies have become a new scientific problem. In this paper, the rare earth elements and C-O, S, Pb and Zn isotopes geochemistry of Pb-Zn orebodies were mainly studied, on the basis of tunnel geological logging and rock-mineral identification. The Pb-Zn ore bodies of Yangla deposit are mainly of skarn type, which are distributed in the edge of skarn type copper bodies in the form of stratiform, irregular veins and lenticular, and co-produced with skarn type copper bodies. It is obviously characterized by branch-compound and ore bodies'''' reappearing after disappearing. The second is hydrothermal vein type, which filled in the structural fracture zone with irregular veinlike shape. Calcite associated with Pb-Zn orebodies can be divided into early mineralization stage calcite (Ⅰ) and late mineralization stage calcite (Ⅱ). The early mineralization stage calcite (Ⅰ) mainly occurs in the Pb-Zn orebodies in irregular clumps, and anhedraal crystal, ΣREE of calcite (Ⅰ) is between 24.05×10-6 and 104.50×10-6, δEu shows positive anomalies, δCe displays weak negative anomalies, chondrite-normalized REE patterns are LREE-rich. The δ13CPDB and δ18OSMOW of calcite (Ⅰ) are between -6.52‰－-4.07‰ and 5.04‰-9.94‰, respectively, indicating that the metallogenic materials are mainly from granitic magma. The late mineralization stage calcite (Ⅱ) is produced veins in the Pb-Zn orebodies, ΣREE of calcite (Ⅱ) is between 28.71×10-6 and 114.60×10-6, δEu shows positive anomalies, δCe displays weak negative anomalies, chondrite-normalized REE patterns are LREE-rich. The δ13CPDB and δ18OSMOW of calcite (Ⅱ) are between -3.81‰－-3.53‰ and 14.36‰-17.30‰, which proves that the ore-forming material comes from the mixing of granitic magma and marine carbonate rocks. Calcite in early and late metallogenic stages are of hydrothermal origin, and there is no significant difference in the content of rare earth elements. The δ34S of sulfide (n=38) in Pb-Zn orebodies are between -2.48‰ and 2.32‰, total sulfur isotope is close to zero, indicating that the metallogenic materials are derived from mantle and deep crust. The lead isotopic variation range of sulfide (n=15) is small, the 208Pb/204Pb, 207Pb/ 204Pb and 206Pb/204Pb range from 38.7501 to 38.7969, 15.7159 to 15.7248, and 18.3640 to 18.3874, respectively, indicating that the lead in Pb-Zn orebodies mainly comes from the upper crust. The δ66ZnJMC of sphalerite (n=5) is between 0.31‰ and 0.44‰, which is obviously higher than other skarn type Pb-Zn deposits, and it also reveals that the metallogenic Zn mainly comes from magma. There is no significant difference between the Pb-Zn orebodies and Cu orebodies in terms of host-rock layers, orebodies attitude, mineral association, ore fabrics, wall rock alteration, ore-controlling factors and isotope composition of C-O, S, Pb, which shows that the Pb-Zn orebodies and the Cu orebodies are of the same origin and are the products of the same metallogenic process. Pb-Zn orebodies is later than the Cu orebodies, which is the product of the late metalogenic stage and distributed at the edge of Cu orebodies. Based on the above research data, the Cu-Pb-Zn metallogenic pattern of Yangla deposit is established in this paper.
Key words: Pb-Zn orebodies; calcite; rare earth element; isotopes; Yangla copper polymetallic deposit; northwest Yunnan province
